Yu Shang

Synthesis, characterization and properties of nitrogen-rich compounds based on cyanuric acid: a promising design in the development of new energetic materials

Nitrogen-rich compounds such as ammonium (1), hydrazinium (2), aminoguanidinium (3), diaminoguanidinium (4), triaminoguanidinium (5), aminonitroguanidinium (6), aminocarbonylguanidinium (7), and metforminium (8), based on a nitrogen-rich anion [CA− (N% = 32.55%, CA = cyanuric acid) and co-crystal 5-amino-1H-tetrazole based on CA (9) were synthesized by means of metathesis reactions. The crystal structures of compounds 2, 4, and 9·H2O were determined by single-crystal X-ray diffraction and fully characterized by UV-vis, FT-IR, 1H NMR, MS and elemental analysis. The thermal stabilities were investigated by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The DTA results show that all compounds exhibit high thermal stabilities. Additionally, the heats of formation were calculated by using the B3LYP functional with the 6-311++G** basis set and a Born–Haber energy cycle. Theoretical calculations provided detonation pressures and velocities of the energetic salts within the range of 16.88–30.71 GPa and 6276.5–8392.1 m s−1, respectively. Impact sensitivities of the compounds were determined by the Fall hammer test. All compounds show insensitive impact sensitivities of >60 J, which are better than those of TATB (50 J).

Nitrogen-Rich Energetic Metal-Organic Framework: Synthesis, Structure, Properties, and Thermal Behaviors of Pb(II) Complex Based on N,N-Bis(1H-tetrazole-5-yl)-Amine

The focus of energetic materials is on searching for a high-energy, high-density, insensitive material. Previous investigations have shown that 3D energetic metal–organic frameworks (E-MOFs) have great potential and advantages in this field. A nitrogen-rich E-MOF, Pb(bta)·2H2O [N% = 31.98%, H2bta = N,N-Bis(1H-tetrazole-5-yl)-amine], was prepared through a one-step hydrothermal reaction in this study. Its crystal structure was determined through single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, and elemental analysis. The complex has high heat denotation (16.142 kJ·cm−3), high density (3.250 g·cm−3), and good thermostability (Tdec = 614.9 K, 5 K·min−1). The detonation pressure and velocity obtained through theoretical calculations were 43.47 GPa and 8.963 km·s−1, respectively. The sensitivity test showed that the complex is an impact-insensitive material (IS > 40 J). The thermal decomposition process and kinetic parameters of the complex were also investigated through thermogravimetry and differential scanning calorimetry. Non-isothermal kinetic parameters were calculated through the methods of Kissinger and Ozawa-Doyle. Results highlighted the nitrogen-rich MOF as a potential energetic material.

Nitrogen-rich energetic salts of 1H,1′H-5,5′-bistetrazole-1,1′-diolate: synthesis, characterization, and thermal behaviors

A series of nitrogen-rich heterocyclic 1H,1′H-5,5′-bistetrazole-1,1′-diolate salts, namely, 1,2,4-triazolium (2), 3-amino-1,2,4-triazolium (3), 4-amino-1,2,4-triazolium (4), 3,5-diamino-1,2,4-triazolium (5), 2-methylimidazolium (6), imidazolium (7), pyrazolium (8), 3-amino-5-hydroxypyrazolium (9), dicyandiamidine (10), and 2,4-diamino-6-methyl-1,3,5-triazin (11), was synthesized with cations. These energetic salts were fully characterized through FT-IR, 1H NMR, 13C NMR, and elemental analysis. The structures of 2, 3·7H2O, 6·2H2O, 8, and 10·4H2O were further confirmed through single crystal X-ray diffraction. Their thermal stabilities were investigated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results indicated that all of the salts possess excellent thermal stabilities with decomposition temperatures ranging from 225.7 °C to 314.0 °C. On the basis of the Kamlet–Jacobs formula, we carefully calculated their detonation velocities and detonation pressures. All of the salts, except 11, exhibit promising detonation performances with a detonation pressure of 20.23–28.69 GPa and a detonation velocity of 7050–8218 m s−1. These values are much higher than those of TNT. The impact sensitivities of the compounds were determined via a Fall hammer test. All of the compounds show excellent impact sensitivities of >50 J, and this finding is higher than that of TATB (50 J). Therefore, these ionic salts with excellent energetic properties could be applied as new energetic materials.

Novel insensitive energetic-cocrystal-based BTO with good comprehensive properties

Combining a layer construction strategy with cocrystallization techniques, we designed and prepared a structurally unusual 1H,1′H-5,5′-bistetrazole-1,1′-diolate (BTO) based energetic cocrystal, which we also confirmed by single-crystal X-ray diffraction and powder-crystal X-ray diffraction. The obtained cocrystal crystallizes in a triclinic system, P-1 space group, with a density of 1.72 g cm−3. The properties including the thermal stability, sensitivity and detonation performance of the cocrystal were analyzed in detail. In addition, the thermal decomposition behavior of the cocrystal was studied by differential calorimetry and thermogravimetry tandem infrared spectroscopy. The results indicated that the cocrystal exhibits strong resistance to thermal decomposition up to 535.6 K. The cocrystal also demonstrates a sensitivity of >50 J. Moreover, its formation enthalpy was estimated to be 2312.0 kJ mol−1, whereas its detonation velocity and detonation pressure were predicted to be 8.213 km s−1 and 29.1 GPa, respectively, by applying K–J equations. Therefore, as expected, the obtained cocrystal shows a good comprehensive performance, which proves that a high degree of layer-by-layer stacking is essential for the structural density, thermal stability and sensitivity.

Synthesis, characterization, and thermal analysis of a new energetic salt based on 1ʹ-hydroxy-1H,1ʹH-5,5ʹ-bitetrazol-1-olate

ABSTRACT 4-Amino-1,2,4-triazolium 1ʹ-hydroxy-1H,1ʹH-5,5ʹ-bitetrazol-1-olate (ATHBTO) was synthesized by reacting 4-amino-1,2,4-triazole (AT) and 1H,1′H-5,5′-bistetrazole-1,1′-diolate dihydrate (H2BTO·2H2O). Its crystal structure was characterized through single-crystal X-ray diffraction. Meanwhile, FTIR, 1H NMR, 13C NMR, and elemental analysis were also introduced to analyze its composition. The thermal stability was investigated by differential scanning calorimetry, thermogravimetric analysis, and thermogravimetric tandem infrared spectrum. Results indicated that ATHBTO exhibited excellent resistance to thermal decompositions reaching 511.4 K and had a 64.6% mass loss between 475.7 and 552.3 K. The kinetics parameters were calculated by Kissinger’s method and Ozawa–Doyle’s method. Moreover, according to the Kamlet–Jacobs formula, the calculated detonation velocity and detonation pressure of ATHBTO attained 8218 m/s and 28.69 GPa, respectively.

Preparation and characterization of insensitive HMX/rGO/G composites via in situ reduction of graphene oxide

Composites of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane/reduced graphene oxide/graphite (HMX/rGO/G) were successfully prepared via an in situ chemical reduction coating method. The morphology, composition and thermal decomposition characteristic of the composites were analyzed by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy and differential thermal analysis (DTA). rGO together with G exhibited a better desensitizing effect than fullerene and carbon nanotubes. When 1.0 wt% GO and 1.0 wt% G were added as desensitizing materials, the impact sensitivity of raw HMX decreased from 100% to 8% and the friction sensitivity decreased from 100% to 0% after in situ chemical reduction coating. Meanwhile, DTA results indicated that rGO and G were compatible with HMX. These combined properties suggest that rGO sheets along with graphite can be utilized as co-desensitizers in HMX explosives.

Synthesis, Crystal Structure and Thermal Decomposition of Triaminoguanidinium 2, 4, 6-Trioxo-1, 3, 5-triazinan-1-ide Based on Cyanuric Acid

A nitrogen-rich energetic compound-triaminoguanidinium 2, 4, 6-trioxo-1, 3, 5-triazinan-1-ide (1) was prepared with a yield of 91% via one-step metathesis reaction using triaminoguanidinium hydrochloride (TAG-HCl) and sodium cyanurate (CANa) as raw materials. The structure of the product was characterized by X-ray single-crystal diffraction, UV-Vis, FT-IR, 1H NMR, mass spectrometry and elemental analysis. The enthalpy of formation and detonation parameters of the product were calculated. Its thermal stability, non-isothermal reaction kinetics and decomposition process were studied by differential scanning calorimetry(DSC) at a heating rate of 10 K·min-1 and thermogravimetric (TG) analysis coupled with Fourier transform infrared spectroscopy (FTIR). The impact sensitivity of the product was determined by the drop hammer test. Results show that the crystal of compound 1 is monoclinic, space group P21/n with a calculated density of 1.676 g·cm-3. Its enthalpy of formation is 327.9 kJ mol-1, the detonation velocity 7900 m·s-1, and the detonation pressure 26.5 GPa. Probable thermal decomposition mechanism of 1 under N2 atmosphere as shown in the text is proposed. Compound 1 is very insensitive to impact, and the impact sensitivity is greater than 60 J, which is better than that of TATB (50 J).